Dental procedures are very common and are necessary for proper dental health, whether it be dental fillings, dental crown applications, root canals, orthodontic work, periodontal surgery, dental cleaning, and many other procedures. One common problem with these dental procedures is that the patient must maintain an open mouth for extended periods of time. The dentist, dental assistant, or dental hygienist must have adequate exposure to access the site to be treated. While opening of the mouth for short periods of time is not problematic for most patients, many, if not most, patients do have difficulty maintaining an open mouth for the extended periods of time required for many dental procedures. All dental patients have at least some difficulty opening their mouths for prolonged periods, as this prolonged opening fatigues the muscles and becomes uncomfortable. Most patients just accept that going to the dentist is uncomfortable and just tolerate the discomfort. Fifty percent of patients have significant difficulty keeping the mouth open for any procedure. This percentage increases with the length of time of the procedure. Elderly, young, and patients on psychotropic drugs have more difficulty that others, but virtually all patients have discomfort opening the mouth for any period of time.
This rather high figure may reflect the prevalence of temporomandibular joint disorders (TMD) in the general population. Epidemiological studies have revealed an average of 30%-44% prevalence of TMD in the general population. All of these patients will experience difficulty at the dentist, with either limited mouth opening or with pain and discomfort in the jaw muscles from straining to keep the mouth open or both. There is also a subset of the population that does not have TMD but that does have difficulty and/or pain with limited mouth opening, due to other causes of muscle tightness. Examples of such causes of difficulty with mouth opening include bruxism, clenching, stress, psychological issues, and others. This segment accounts for as much as 20% of the population. Hence, well over 50% of the population may have difficulty with prolonged mouth opening for dental procedures.
The typical reason for difficulty with prolonged mouth opening is muscle fatigue and spasm that initially becomes uncomfortable but progresses to become quite painful. The human mouth is a simple hinge, with the mandible articulated with the skull at the temporomandibular joint. The muscle systems that cause the mandible to close are mainly the large masseter muscles and the temporalis muscles. These are robust and responsible for forceful chewing, mastication, clenching, bruxing, etc. The corresponding muscles responsible for opening the mouth are mainly the small and delicate pterygoid muscles. This causes a disparity in the opposing muscle groups, which is not of importance in the normal function of the mouth during usual activities such as eating, drinking, speaking, and the like. However, prolonged opening of the mouth is affected by, and very difficult because of, the size, disparity, and arrangement of the opposing muscle sets. The smaller pterygoid muscles tire after several minutes of prolonged opening, causing discomfort and actual pain.
This creates a dilemma, as the dental practitioner must have access to the oral cavity to perform the necessary task, but frequently the simple act of holding the mouth open is uncomfortable to the patient. Devices that assist in holding the mouth open have been in use for many years for this reason. These consist of bite blocks, which are simple wedge devices placed between the teeth to prop open the mouth by creating a consistent space between the upper teeth and lower teeth by depressing the mandible. Bite blocks are used on one side of the jaw or the other to allow access for procedures, and this asymmetrical use can strain the temporomandibular joints, often triggering joint pain. Use of a bite block also creates a persistent and continuous stretching of all the muscles that affect the depression of the mandible, i.e., the pterygoids, or elevation of the mandible, i.e., the masseters and the temporalis groups. These devices offer no period of relaxation for the muscles to recover from the stress of the continuous stretching. This lack of a relaxation period can result in pain and discomfort to the patient. The bite blocks also occupy space within the oral cavity and impede access or exposure to the specific area that needs attention or treatment.
Other known devices have been developed that prop the mouth open but are almost universally awkward to employ, as they also frequently inhibit access to all parts of the oral cavity and the dental practitioner must navigate around these devices to perform the necessary and intended maneuvers. They also provide a continuous and persistent stretching of the musculature, which results in discomfort while attempting to assist in keeping the mouth open. The bite blocks commonly used actually stimulate contraction of the muscles responsible for closing the mouth and accentuate the problems and difficulties.
In U.S. Pat. No. 6,030,217, Fletcher describes a device comprised of a flexible mouth piece that fits over the lower front teeth and an elongated flexible member attached at one end to the mouth piece and the other end to a handhold object. Fletcher's device may suffer from limitations that preclude optimal functioning to assist with opening the mouth and maintaining it open in a comfortable position in a safe manner. For instance, the mouth piece has sufficient flexibility to permit the mouth piece to bend and release from the lower teeth when the flexible member is subjected to a selected threshold tension. This, in essence, means that the mouth piece will typically flex and become disengaged from the lower teeth if the patient exerts more downward force than the mouth piece will tolerate. With significant downward force being exerted and an abrupt release by the mouth piece, the mouth piece may be forcefully be propelled or pulled downward toward the hand. As soon as the trailing edge clears the teeth, it may engage the lower lip with significant abrupt downward force, and at the very least, bruise the lower lip if not lacerate it. As well, the mouthpiece may be propelled as a missile toward the hand, where it may impact the hand, fingers, or other body part or even the dentist or dental assistant. Just the thought of a piece of plastic flying about the dental operatory, contaminating equipment and personnel with saliva, enough to discourage the use of such a device.
Additionally, since any incremental tension may be at least partially, if not mostly, absorbed by the flexible mouth piece of Fletcher, rather than transferred to the mandible, the mouth piece will bend or deform, instead of providing additional consistent, graded and gradual downward pressure on the mandible. Slow and gradual increases in tension downward are often needed for maximum relaxation and stretching. Hence, the flexible mouthpiece of Fletcher may be limited for this reason as well.
Moreover, the elongated flexible member of Fletcher can create an unlimited number of angles and directions in which the downward force may be directed. The elongated flexible member of Fletcher may introduce variability in the use of the device, which also can be a safety issue. The teeth may be accustomed to downward pressure and are very stable when pressure is in the same plane as the long axis of the tooth. If the force is downward and forward, or downward and to one side or the other, the tooth or teeth may be loosened or tilted. Marginally loose teeth from periodontal disease or other causes could be loosened even more than at their resting state. The temporomandibular joint (TMJ) may also be damaged by inappropriately directed forces. Tension forward or outward may even dislocate the TMJ, and tension to the side may cause TMJ dysfunction or worsen TMJ preexisting conditions. With so many variations in the direction of the force, it may be exceedingly difficult to align the flexible member, the mouth piece and the handhold object so that the proper direction of the force is maintained during the entire dental procedure, which may last for an hour or longer. Hence, the flexible member of Fletcher may be convenient to connect the mouth piece with the handhold object, but it may be dangerous to the patient and the staff for a number of reasons, and it may create unintended problems and difficulties.
Additionally, there may be a need for devices or methods that increase the degree of opening of the mouth beyond passive opening using the muscles of the jaw or opening with a simple assist device. Not only do patients experience discomfort from having the jaw open for protracted periods, but the limited exposure to the dental operative field constantly constrains the dental practitioner. The ability to open the mouth maximally diminishes with the time the mouth is open, as the muscles fatigue and less than a fully open position is sought for comfort reasons. The practitioner is forced to operate and perform procedures within the mouth, which is basically a small hole, and that hole becomes smaller with time. The wider the patient is able open the teeth, the better the exposure for the dental practitioner and the less tedious the work becomes.
No known prior art devices are targeted improving the degree of opening the mouth or providing more exposure as the procedure progresses. Bite blocks act as props, and the Fletcher device may either prop or distract the mouth open, but this is where these devices stop. The bite blocks are forced between the upper and lower molars and may actually trigger a reflex to bite down. They certainly do not continue to improve the degree of opening. The Fletcher device may assist in opening the mouth and may reduce the discomfort despite the significant limitations and safety issues it presents, but it does not continue to improve the opening of the mouth and continue to improve the exposure available to the dentist. While the prior art includes devices that attempt to address the mouth-opening problem, all of these devices have shortcomings, as discussed above.
Another major limitation of known prior art devices is that they are all placed into the mouth, in addition to other devices used in a procedure. In other words, they are additive devices and occupy valuable space in the mouth, which limits the access by the dentist or hygienist in addition to the other tools that may be used. For example, while many different tools and devices may be used during a dental procedure, suction is used almost universally in dental procedures. Hence, the known prior art devices must be inserted in addition to the suction apparatus. This may become awkward and confusing, for example, if the patient is responsible for the suction with one hand and the Fletcher prior art device with the other hand. More importantly, the space occupied by a combination of suction tube and the prior art devices may well impede access to the mouth by the dentist. There is the probability of simply having too many items in the mouth at one time to allow easy access.
Therefore, it would be very desirable to have improved devices and methods for maintaining a mouth in an open position for prolonged periods of time for dental procedures. Ideally, these devices and methods would provide improvements over the prior art devices and methods and would reduce or eliminate at least some of the discomfort and pain of maintaining an open jaw. Also ideally, such devices and methods should work well for patients while not overly obstructing the dentist's access to the mouth for performing procedures. The embodiments described herein will meet at least some of these objectives.